1. Field of the Invention
The invention relates to methods for stabilizing nucleic acid triplexes.
2. Description of Related Art
Oligonucleotide third strands can bind to double-stranded nucleic acids to form triple-stranded helices (triplexes) in a sequence specific manner. The third strand binding code (a complementarity principle) dictates the sequence specificity for binding third strands in the major groove of double-stranded nucleic acids to form a triple-stranded helix or triplex. The code provides the specificity of third-strand binding for design of gene-based therapeutic agents that bind specifically to target nucleic acid sequences with little or no non-specific binding to non-target sequences. The third strand binding code, as well as various utilities for triplexes, are described in U.S. Pat. Nos. 5,422,251 and 5,693,471 to Fresco, which also shows ionic conditions such as the presence of Mg+2, Mn+2, Ca+2, Na+, Li+, K+ or tetramethylammonium cations suitable for triplex formation.
The present invention relates to methods for enhancing the stability of a triplex formed from one or more nucleic acid strands in a solution, said method comprising adding to the solution, either before or after formation of the triplex, an effective amount of either of the following:
(a) a water structure-making substance other than an alkali or alkaline earth metal cation, a tetramethylammonium cation, or a polyamine; or
(b) a combination of said water structure-making substance and an alkali or alkaline earth metal cation a tetramethylammonium cation, or a polyamine.
The present invention further relates to a method for forming a triplex from one or more nucleic acid strands, said method comprising adding to a solution, in any order, the strand(s) and an effective amount of one of the following:
(a) a water structure-making substance other than an alkali or alkaline earth metal cation, a tetramethylammonium cation, or a polyamine; or
(b) a combination of said water structure-making substance and an alkali or alkaline earth metal cation, a tetramethylammonium cation, or a polyamine; and allowing said triplex to form.